Element of hatred under Stalin's lead (6)
I believe the answer is:
sodium
'element' is the definition.
(sodium is a kind of element)
'hatred under stalin's lead' is the wordplay.
'hatred' becomes 'odium' (odium is a kind of hatred).
'under' is a charade indicator (letters next to each other).
'lead' indicates taking the first letters.
The first letter of 'stalins' is 's'.
'odium' after 's' is 'SODIUM'.
'of' acts as a link.
(Other definitions for sodium that I've seen before include "1 down, symbol Na" , "Soft metal, symbol Na" , "Element in common salt" , "Atomic number 11" , "Soft reactive metal" .)